WPR11FA155 · Muse KR2

The pilot had no previous experience flying the experimental airplane, although he did have the last registered owner give him a 1-hour overview of the airplane, including a demonstration of the flight controls. The pilot appeared to be rushed and departed in the airplane without performing a test flight. There was no record of the pilot receiving a weather briefing. The previous registered owner said that the airplane did not perform well in windy conditions due to its weight and design.

The airplane departed and proceeded south while gradually ascending and leveling off about 9,500 feet mean sea level (msl). About 30 minutes after departure, the airplane turned to an easterly direction and began a 12-minute ascent to 14,800 feet msl. The airplane proceeded in a meandering southeasterly course and descended to 12,000 feet msl. About 30 minutes later, the airplane turned to a meandering easterly course and started another gradual descent to 7,000 feet msl. During the last 12 minutes of the flight, the altitude fluctuated between 5,800 and 7,300 feet msl. The final radar return was located 1 mile west of the accident location and showed the airplane 1.5 hours after departure, at 7,100 feet msl (5,170 feet above ground level).

In the vicinity of the accident site, around the time of the accident, there was a westerly surface wind at 40 mph, gusting to 56 mph. The highest surface wind was reported north of the accident location with wind gusts up to 73 mph. At 9,500 feet msl, the wind was from 245 degrees at 28 knots, which resulted in a strong local vertical wind shear capable of producing moderate or greater turbulence in the layer. Several pilots operating in the area of the accident site reported encountering updrafts and downdrafts, from 1,500 to 2,500 feet per minute, and unusually strong low-level wind and turbulence.

The airplane debris field was comprised of large heavy debris (engine and landing gear) near the location of the initial impact and lighter debris that was distributed downwind. Two items, a 2-foot-long section of vertical stabilizer and an 8-inch piece of rudder skin, were found 1,820 feet and 2,880 feet (respectively) downwind from the main debris scatter area, significantly farther from the main debris scatter area, which would indicate these two items were the first to depart the airplane. The overall debris pattern, and lack of damage to the wings is consistent with an in-flight breakup of the airplane. The rapid descent was probably initiated by the separation of about half of the vertical stabilizer as a result of severe turbulence while the airplane was near the location of the final radar return. The departure of a portion of the vertical stabilizer and pieces of the rudder would have resulted in the pilot’s inability to control the airplane, followed by a rapid descent and subsequent in-flight breakup.

Verbatim NTSB analysis and probable cause from the NTSB dataset